Detection of combined frequency and amplitude modulation. C, B., Moore, J., & Sek, A. Acoustical Society of America, 92:3119-3131, 1992.
abstract   bibtex   
This article is concerned with the detection of mixed modulation (MM), i.e., simultaneously occurring amplitude modulation (AM) and frequency modulation (FM). In experiment 1, an adaptive two-alternative forced-choice task was used to determine thresholds for detecting AM alone. Then, thresholds for detecting FM were determined for stimuli which had a fixed amount of AM in the signal interval only. The amount of AM was always less than the threshold for detecting AM alone. The FM thresholds depended significantly on the magnitude of the coexisting AM. For low modulation rates (4, 16, and 64 Hz), the FM thresholds did not depend significantly on the relative phase of modulation for the FM and AM. For a high modulation rate (256 Hz) strong effects of modulator phase were observed. These phase effects are as predicted by the model proposed by Hartmann and Hnath [Acustica 50, 297-312 (1982) ], which assumes that detection of modulation at modulation frequencies higher than the critical modulation frequency is based on detection of the lower sideband in the modulated signal's spectrum. In the second experiment, psychometric functions were measured for the detection of AM alone and FM alone, using modulation rates of 4 and 16 Hz. Results showed that, for each type of modulation, d' is approximately a linear function of the square of the modulation index. Application of this finding to the results of experiment 1 suggested that, at low modulation rates, FM and AM are not detected by completely independent mechanisms. In the third experiment, psychometric functions were again measured for the detection of AM alone and FM alone, using a 10-Hz modulation rate. Detectability was then measured for combined AM and FM, with modulation depths selected so that each type of modulation would be equally detectable if presented alone. Significant effects of relative modulator phase were found when detectability was relatively high. These effects were not correctly predicted by either a single-band excitation-pattern model or a multiple-band excitation-pattern model. However, the detectability of the combined AM and FM was better than would be predicted if the two types of modulation were coded completely independently.
@article{ BrianC1992,
  abstract = {This article is concerned with the detection of mixed modulation (MM),
	i.e., simultaneously occurring amplitude modulation (AM) and frequency
	modulation (FM). In experiment 1, an adaptive two-alternative forced-choice
	task was used to determine thresholds for detecting AM alone. Then,
	thresholds for detecting FM were determined for stimuli which had
	a fixed amount of AM in the signal interval only. The amount of AM
	was always less than the threshold for detecting AM alone. The FM
	thresholds depended significantly on the magnitude of the coexisting
	AM. For low modulation rates (4, 16, and 64 Hz), the FM thresholds
	did not depend significantly on the relative phase of modulation
	for the FM and AM. For a high modulation rate (256 Hz) strong effects
	of modulator phase were observed. These phase effects are as predicted
	by the model proposed by Hartmann and Hnath [Acustica 50, 297-312
	(1982) ], which assumes that detection of modulation at modulation
	frequencies higher than the critical modulation frequency is based
	on detection of the lower sideband in the modulated signal's spectrum.
	In the second experiment, psychometric functions were measured for
	the detection of AM alone and FM alone, using modulation rates of
	4 and 16 Hz. Results showed that, for each type of modulation, d'
	is approximately a linear function of the square of the modulation
	index. Application of this finding to the results of experiment 1
	suggested that, at low modulation rates, FM and AM are not detected
	by completely independent mechanisms. In the third experiment, psychometric
	functions were again measured for the detection of AM alone and FM
	alone, using a 10-Hz modulation rate. Detectability was then measured
	for combined AM and FM, with modulation depths selected so that each
	type of modulation would be equally detectable if presented alone.
	Significant effects of relative modulator phase were found when detectability
	was relatively high. These effects were not correctly predicted by
	either a single-band excitation-pattern model or a multiple-band
	excitation-pattern model. However, the detectability of the combined
	AM and FM was better than would be predicted if the two types of
	modulation were coded completely 
	
	independently.},
  added-at = {2012-01-27T14:10:42.000+0100},
  author = {Brian C, J. Moore and Sek, Aleksander},
  biburl = {http://www.bibsonomy.org/bibtex/26b8ca785c8d9bd26cd7494a83b44e583/muhe},
  file = {Detection of combined frequency and amplitude modulation.pdf:1992\\Detection of combined frequency and amplitude modulation.pdf:PDF},
  interhash = {6f5196bfcaa3263a741029c46762b249},
  intrahash = {6b8ca785c8d9bd26cd7494a83b44e583},
  journal = {Acoustical Society of America},
  keywords = {Wahrnehmung Wirkung und},
  owner = {Mu},
  pages = {3119-3131},
  pdf = {English\没什么用的\Detection of combined frequency and amplitude modulation.pdf},
  title = {Detection of combined frequency and amplitude modulation},
  volume = {92},
  year = {1992}
}

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